Description of Related Art
Lyophilisation tanks are used for treating products or substances generally contained in small sized vials. Advantageously, these vials are distributed as compactly as possible over several racks disposed above each other inside the tank. It is obviously indispensable to reduce the time for loading and unloading the racks or any other intermediate device as much as possible, so that the downtime of the tank, namely the time during which it is not operational, is as short as possible, for reasons of profitability but also to avoid as much as possible that the tank is in communication with the outside atmosphere for too long a time and so that water does not thus condense on the cold surface of the parts inside the chamber.
The arrangement is known which consists in using a carriage of constant height which moves at the level of an orifice giving access to the tank and arranging for the racks to be loaded or unloaded to be able to move each in their turn in the tank and to come up to the corresponding height. Compartments previously loaded with the product and disposed on the platform of the carriage are then transferred manually, for example by letting them slide over an extension of the platform in the direction of the tank.
It will be readily understood that this manual method of loading is slow and time-consuming and that it involves upstream or downstream work for pre-storing in the compartments which is quite incompatible with the above mentioned requirements of speed.
Tray transfer installations are also known for automatically loading the trays on said racks, which installations comprise an intermediate mobile transfer platform which is for example formed of a frame with wheels or rollers driven in rotation for moving each tray. Although automatic, these installations are not necessarily faster; they are in any case complicated and costly to use and require the manufacture and storage of a large number of appropriate trays.
Other automatic loading and unloading systems exist also which do not use transfer trays or compartments but which enable a set of vials to be introduced, by causing them to slide over a feed table. For that, the vials may be recovered on a transport belt which conveys them from the packing station as far as this table on which they are compactly assembled before being introduced, in batches, inside the tank, for example under the action of a pusher rake.